Microelectromechanical (MEMS) devices have found many applications in basic signal transductions. For example, MEMS-based spatial light modulators are transducers that modulate incident light in spatial patterns in response to optical or electrical inputs. The incident light may be modulated in phase, intensity, polarization, or direction. This modulation may be accomplished through the use of a variety of materials exhibiting magneto-optic, electro-optic, or elastic properties. Such spatial light modulators have many applications, including optical information processing, display systems, and electrostatic printing.
A micromirror-based spatial light modulator is a spatial light modulator that consists of an array of micromirrors and an array of electrodes and circuits. A typical micromirror has a deformable reflective mirror plate attached to a deformable hinge that is held on a substrate such that the mirror plate can rotate to different positions. According to the different rotation positions of the mirror plate, operation states, such as ON and OFF states in a binary operation mode, are defined. In the ON state, incident light is reflected so as to produce a “bright” pixel on a display target, and in the OFF state, incident light is reflected to produce a “dark” pixel on the display target. In an application of displaying an image represented by image pixels having “bright” and “dark” values, the micromirrors are associated with the image pixels, and the micromirrors are individually set to the ON or OFF states according to the “bright” or “dark” values of the image pixels associated with micromirrors. The collective effect of the reflection from the micromirrors at the ON and OFF states for a given incident light is reproduction of the image on the display target.
The deflections of the mirror plates are accomplished through the electrodes and circuits connected to the electrodes. Specifically, each mirror plate of a micromirror is electrostatically coupled to one or more electrodes such that an electrostatic field can be established between the mirror plate and the electrode(s) for deflecting the mirror plate. The strength of the electrostatic field is determined by the voltage of the electrode, and voltage of the electrode is controlled by the output voltage of the circuit, which can be a memory cell, such as a DRAM. With this configuration, the micromirrors can thus be individually addressed and the mirror plates of the micromirrors can be individually deflected.
Therefore, a method for making the micromirror device, micromirror array device, and spatial light modulator comprising the micromirror array devices is desired.